Questions About HIV Testing

[aquaman604]

Hi Doc,

I just have a few questions about HIV testing. It's been 4 months since my last exposure.

I have read from many sources about the window periods for HIV testing and I am very confused and would like some clarification.

1) I see that on this forum, as well as other sources, it is stated that nearly 100% of all infections will be detectable withing 6-8 weeks. However, other places (such as the CDC and other sources) states that only 97% of all infections are detectable within 3 months and an HIV test isn't conclusive til 6 months. Why is there such a difference in window periods?

2) I understand that HIV testing technology has something to do with the window period but how does having a newer generation HIV test result in your body making antibodies quicker?

3) What kind of factors affect seroconversion periods? Why do some people take longer than others? Does stress/anxiety affect the seroconversion period?

4) I have had an HIV test at 3 months and it came out negative (thank god) but I have had the maculopapular "HIV rash" on my back for over a month. This is the first time I've ever had this kind of rash. Do you suggest further testing? If not, what kind of other conditions can cause similar rashes?

5) Is the window period for HIV-2 the same as that of HIV-1? If so, are rapid tests that test for both HIV-1 and HIV-2 equally accurate for both? (I took the Oraquick Advance Oral HIV test)

6) Is ARS for HIV-1 and HIV-2 similar, in both type and time it happens? Is it possible to get ARS symptoms (i.e. my maculopapular rash) 2-3 months after my last exposure?

7) Lastly, I have read on Bloomberg that the Oraquick Advanced test gave out at least 8% false-negatives in the Seattle, WA area. Should I be worried about a false positive as this is the test that I took?

I know that its a lot of questions. Thanks for taking the time Doc!

[Edward W Hook, MD]

Most of what is known about HIV-2 paralells data for HIV-1.  You state your rash has been present for more than a month - the ARS rash does not last that long. There is just NO reason for you to think you have HIV - end of story. More "what if" questions really are not going to persuade me otherwise.

Finally, beware if the internet. I can assure you that you can find just about any answer you want to just aobvut any question.  Many of those answers are just plain wrong.  Consider your sources and decide what sites you wish to believe.  We will not debate internet generated misinformation on this site, sorry.  Hope this helps.  Take care.  EWH

[aquaman604]

Sorry to be asking so much but I just keep finding things online that fuel my anxiety.

You responded that less is known about the window periods for HIV-2. Since less is know as to when the antibodies develop, is there any way that I can know for sure with a negative test that I do not have HIV-2 (although I do realize that it is HIGHLY unlikely)? My last exposure 4 months ago was in South Korea.

I ask this because I found this case report about HIV-2 and their relationship with rashes/hyperpigmentation (which is pretty much what I have):

http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijaai/vol2n1/hiv.xml

Supposedly this individual had acquired HIV-2 in the United States and developed a rash. I promise this will be my last question. Can you elaborate? Thanks Doctor

[Edward W Hook, MD]

They work like other tests and will detect HIV-2 as well as 1 infections.  Read my answer above to your second question.  Less is known about "window" periods for HIV-2 than HIV-1.  EWH

[aquaman604]

I'm a little confused about the answer to #5. Are rapid tests that screen for HIV1/2, equally accurate for detecting both? And are the window periods the same for both?

[aquaman604]

Doctor, for question #7, I meant to ask if I should be worried about a false-negative. I mistakenly wrote false positive.

[Edward W Hook, MD]

You've asked a number of good questions.  I will go straight to them:

1.  Time to a positive test.  There are not differences in the data on which recommendations are made, just the thresh-hold of various sites for uncertainty.  Here on this site our recommendations are made relative to specific situations (in most instances) allowing us to tailor our responses to the circumstance.  In contrast, agencies like the CDC have no threshold for acceptance of uncommon events and provide very general data.  The data on seroconversion to HIV are that at 4 weeks 85-90% of persons who are going to get a positive test will, by six weeks it is up to 95%, at eight weeks - 98-99% and by 12 weeks virtually all tests that are going to be positive will be.

2.  Your body has and will always make antibodies in the same way.  As tests have gotten better they give their results sooner after exposure.

3.  Very little effects seroconversion time other than taking antiretroviral therapy.  Stress, antibiotics and other infections have no effect.

4.  No, the rash you describe is due to something else.  Believe your 3 month test result.

5.  As best we know. Most of the literature on the ARS is for HIV-1.  Some tests for HIV which favor HIV1 will give an indeterminate test such that when the confirmatory western blot or other test is performed the diagnosis of HIV-2 (which is far rarer than questions about it) will be made.

6.  See above.  Stop worrying about ARS, you have a negative test at 3 months.

7.  The study in Seattle is one report (not even a carefully conducted study) which differs in its conclusions from other well done studies.  Dr. Handsfield who lives in Seattle tends to discount this report somewhat.  False negatives are a little bit more common in the rapid tests but not dramatically or significantly so.  

EWH